Ancient organism remains, fossil layers, similarities among organisms alive today, similarities in DNA and similarities of embryos.
        
             
        
        
        
<u>Answer</u>:  Cystic fibrosis is a genetic disorder that causes thick mucus secretions.
<u>Explanation</u>:
- <em>Cystic fibrosis</em> is a genetic disorder caused by mutations in a gene that makes a protein called CFTR (cystic fibrosis transmembrane regulator).
-  The CFTR protein normally functions as a channel for transport of chloride ions in cells responsible for mucus production.
-  A person suffering from cystic fibrosis produces abnormal CFTR protein or no CFTR protein at all.
- This is the  reason that thick, sticky mucus is produced instead of the thin, watery kind.
 
        
                    
             
        
        
        
 The Outline  of the top-down effects on bacteria in the four mesocosms is 
- Zooplankton is bacterivores that help keep bacteria populations in Check.
-  Ingestion of zooplankton by fish leads to a rise in bacteria levels. 
<h3>What are 
mesocosms?</h3>
Generally, mesocosms are defined as any outdoor experimental system that investigates the natural environment in a controlled setting and may be thought of as a mesocosm.
In conclusion, Overview of top-down influences on bacterial growth in four mesocosms
To put it another way, zooplankton is bacterivores that play a role in maintaining a healthy bacterial balance.
Fish-eating zooplankton may cause an increase in bacteria in the water.
Read more about mesocosms  
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Answer:
Ocean circulation patterns is directly linked with the marine ecosystem. El Nino event hinders the climate interaction of ocean.  
Explanation:
- The disturbance in the ocean climate interaction transfers the essential nutrients into the deep down ocean leaving very tiny amount at the surface. It lacks the support to plankton growth.
- Ocean circulation patterns can sometime make the ocean food ecosystem less productive.
- El Nino event reverses the ocean current. Surface waters in the central and eastern Pacific Ocean become significantly warmer than usual during this event. So the drifting starts towards east direction (normally driven west).